The present invention relates to a device for the ejection of ground coffee pressed into a cake from a brewing apparatus of a coffee machine comprising an ejection part which is swivelingly fastened to a brewing cylinder.
The preparation of coffee by means of coffee machines is carried out according to different processes which may be separated into two basic types. A first type of process, in which the hot water runs through the ground coffee in a filter solely owing to gravity, is distinguished from a second type of process, in which the hot water is conveyed through the ground coffee under pressure (espresso or pressure-brewing process). The present invention relates particularly to the last-mentioned pressure-brewing process. For carrying out this process automatically, various coffee machines are known in the art. There are those in which, at the end of a brewing operation, the leached-out ground coffee is pressed into a cake which must thereafter be removed from the brewing apparatus. For that purpose, the cake of ground coffee is first conveyed to one end of the brewing cylinder by means of a piston disposed in the brewing cylinder, longitudinally displaceable relative to the latter. A device for ejection is then actuated in order to strip the cake of ground coffee off the face of the piston and remove it from the brewing apparatus.
It is essential that the cake of ground coffee often adhering to the end surface of the piston, which is customarily provided with a strainer, is removed as completely as possible. In order to reach this goal, more or less expensively designed ejection devices have already become known. It is often necessary to assist the complete removal of the cake of ground coffee by means of a stream of water or by means of a brush.
In the French patent application published under the number FR 2 562 782, an ejection device is disclosed which is very simply constructed. A bent two-armed lever is mounted swivelingly on the frame of a coffee machine. One of the lever arms has at its end a stripper sheet which can be led over the top of the brewing cylinder upon swiveling of the lever. The other lever arm enters into contact with the rods of a crank assembly whenever the swiveling movement is supposed to be carried out. What is disadvantageous about the disclosed ejection device is that the stripper plate describes a circular orbit over the flat brewing-cylinder end having a radius which substantially corresponds to the length of the one lever. The space between the stripper plate and the flat face, provided with a strainer, of the piston at the end of the brewing cylinder is variable during the stripping operation of the cake of ground coffee. Depending upon the adhesion of the cake of ground coffee to the strainer, it will be removed entirely or only partially.
Because the crank assembly is the drive element, the disclosed coffee machine is likewise not suitable for processing varying amounts of ground coffee which is demanded of new coffee machines. Known ejection devices in coffee machines which process varying amounts of coffee are, however, of more complicated construction than the one just described.